The use of synthetic materials such as polyester fiber (DACRON.TM.) or polytetraflurorethylene (PTFE)(TEFLON.TM.) as implants designed to replace diseased or damaged body parts has been extensive. These materials have however, enjoyed limited success. This has been due to the poor biocompatibility of these materials which among other problems, frequently initiate persistent inflammatory reactions. Additionally, the failure of the body to integrate these materials, because they do not break down and do not lend themselves to remodeling by tissue cells that may come into contact with them, causes further problems.
Efforts to use animal or human materials have also been unsatisfactory when these materials are cross-linked by formaldehyde or glutaraldehyde, for example. The process of generalized aldehydic cross-linking renders biomaterials sufficiently unrecognizable to tissue cells so that normal remodeling and integration are not promoted. Similarly, other types of chemical processing of animal or human biomaterials, such as extraction with detergents, or hypertonic buffers or hypotonic buffers can alter them to the degree that they are ineffective in promoting angiogenesis and in stimulating repair and remodeling processes needed for the conversion of an implant into a functional substitute for the tissue or organ being replaced.
A third approach has been that of reconstituting tissue and organ equivalents from structural matrix components, such as collagen, for example, that have been extracted and purified and combined with specialized cells. The process depends upon interactions between the cells and matrix proteins that the cells condense and organize. While tissue-like constructs have been fabricated and been shown to somewhat resemble their natural counterparts, they do not readily develop the matrix complexity characteristic of the actual tissues they are meant to imitate. See, for example, U.S. Pat. Nos. 4,485,096 and 4,485,097, E. Bell, 1984.